SEISMIC DESIGN PARAMETERS for New Buildings at College, San Bernardino,

PROJECT DESCRIPTION San Bernardino Valley College (SBVC) is built on the San Bernardino Valley segment of the San Jacinto . The right-lateral strike-slip San Jacinto fault is thought capable of generating an upper bound (UBE) of moment magnitude Mw=7.3. Earth Consultants International (ECI) was asked to study the seismically induced ground motions at the SBVC site. The purpose of the project was to quantify the strong ground motion anticipated at SBVC due to local . We explored the code-based methodology using a 10% probability of exceedance in 100 years. This is the definition of UBE which the California Geological Survey recommended at that time for critical structures. We also looked at fault-specific San Bernardino Valley College in relation to earthquakes and ground motions that could cause the major Quaternary faults in the region damage at SBVC.

SOLUTION ECI determined an upper bound earthquake for SBVC based on geologic, tectonic, kinematic and seismo lo gical facto rs. We calcu lated th e probabilistic peak horizontal acceleration (PGA) and spectral acceleration with a 10 percent probability of exceedance in 100 years for all faults within 100 km of SBVC using site-specific data and published attenuation relationships. We developed 5 percent damped, uniform risk design response spectra, and compared it to the California Building Code (CBC) and International Council of Building Officials (ICBO) design code standards in effect then. International strong ground motion databases were searched to obtain time history records of ground displacements caused by recent large Average 5% damped uniform response spectra and earthquakes near the site, and source parameters spectra for different attenuation relations pertinent to SBVC. The ground motion estimates obtained for SBVC are high compared to many other parts of because the campus is built directly on the and within 6 km of the San Andreas fault. Therefore, SBVC must be prepared for very strong ground motions at the campus.

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